1. Field of the Invention
The present invention generally relates to a backlight device for a liquid crystal module. More specifically, the present invention relates to a backlight device for a liquid crystal module.
2. Background Information
A conventional liquid crystal module includes a liquid crystal cell and a backlight device. The backlight device is disposed directly behind the liquid crystal cell.
The backlight device mainly includes a linear light source, a light reflecting member, a plurality of optical sheets and a frame. The linear light source includes a straight tube or U-tube fluorescent tube. Electrodes at the ends of the linear light source are fitted into a power socket. The light reflecting member is disposed at the back of the linear light source. The light reflecting member includes a reflecting face. The light from the linear light source is reflected by the light reflecting member, and shines from the back onto the liquid crystal cell. The optical sheets include a light diffusing plate, and are disposed in the required type and number between the light reflecting member and the liquid crystal cell. The light reflected by the reflecting face of the light reflecting member passes through the optical sheets, and shines on the liquid crystal cell from the back, which maintains the brightness balance of an image display face of the liquid crystal cell. The frame supports the linear light source, the light reflecting member and the optical sheets. The frame is made of molded resin or sheet metal.
The linear light source and the light reflecting member are mounted in the frame. All or substantially all of the surface of the light reflecting member is a reflecting face. The reflecting face is divided into one wide, rectangular center region located at the back of the linear light source, and slender, trapezoidal peripheral regions that are raised up in a slanted orientation from four sides of the center region.
With the conventional backlight device, the light reflecting member is formed by combining a sheet that can be bent, and frame pieces. The frame pieces are formed from resin by injection molding.
The sheet is bent along straight bending lines set at places near the two long sides, and has a silhouette shape that is substantially rectangular. The sheet is bent and held so that the rectangular center region and two of the trapezoidal peripheral regions on either side of the center region are formed in the sheet. In the two peripheral regions formed by the sheet, the ends in the lengthwise direction of each of the peripheral regions are formed in a shape such that the spacing between the ends of each of the peripheral regions widens moving away from the bending lines. Thus, the peripheral regions are formed in a trapezoidal shape.
The frame piece is a resin molding formed by injection molding. The frame piece has a slender, slanted, trapezoidal reflecting face. The frame pieces are disposed symmetrically on either side in the lengthwise direction of the sheet. The slender, trapezoidal reflecting faces of the frame pieces are used as the other two peripheral regions. The ends of the slender, trapezoidal reflecting faces of the frame pieces are butted against the ends of the slender, trapezoidal peripheral regions formed by the sheet, and the butting configuration of the four peripheral regions forms a rectangular shape.
Meanwhile, with another conventional backlight device, the light from a light source is reflected by a reflecting plate (see Japanese Laid-Open Patent Application Nos. 2004-102119 and 2004-55182, for example). In the conventional backlight device, uneven brightness is avoided by providing a peaked portion to the reflecting plate. Furthermore, warping of the reflecting plate is prevented by using a multilayer structure for the reflecting plate.
However, when the light reflecting member is a combination of the sheet with the two frame pieces, three components are required to form the light reflecting member, namely, the sheet and the two frame pieces. This not only increases the cost, but also makes the assembly process more complicated and diminishes productivity.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved backlight device. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.